This invention relates to a method of evaporating a solution in one or several evaporation stages, where in each evaporation stage solution is circulated between a heat exchanger and an evaporating vessel, and steam is withdrawn from the evaporating vessel, and where during the evaporation substances from the solution form crusts. These crusts frequently occur in the vicinity of the heating surfaces of a heat exchanger.
In evaporation plants, there must frequently be expected encrustations which impede the further operation or make it necessary to switch off or clean encrusted parts of the plant. When solutions are evaporated to crystallization, crusts as a result of impurities in the solution are frequently formed already in evaporation stages without crystallization through deposition of impurities.
During the removal of the crusts, there is usually required a time-consuming disassembly of the plant components. When cleaning is effected by means of a high-pressure water jet, this is expensive and not harmless. In some cases, a pre-treatment with special chemicals must be effected prior to the high-pressure cleaning, so as to render the crusts attackable for the high-pressure cleaning. In other cases, crusts are dissolved by means of chemicals. This involves the additional problem of the disposal of these chemicals.